Chocolate

I've had my wheels for about a year and a half and I'm ready for a change. The original wheels are 215/60/R16, mine are 225/45/R18. I can honestly say that ride quality is excellent, at 29 PSI. At 32 PSI it is still good but noticeably firmer (though the same could be said if you ran a 16" tire at 32 PSI). However, there is a greater risk of wheel damage running at a lower PSI.



For my next set of wheels, I'm thinking of going 17". The standard size for 17" fitment (and the one used on 05 and later models of the ES) is 215/55/17, which will be the closest match for speedometer accuracy. I don't mind it being off 2 or 3 percent, though, if it means a better ride quality. My question is, would the extra .21 inches of extra sidewall of the 225 contribute to better absorption of vibration or would the 225's extra .4 inches in width offset the effect of any sidewall increase? Thanks.

bitkahuna

iTrader: (20)

extra width, more noise. extra height, better absorbtion/comfort.

mmarshall

All else equal, extra width not only means more road noise, but less traction on wet/slick roads and MORE traction on dry ones....especially with high-performance tires. That's because a wider tire, according to the laws of physics, spreads its weight (and the weight of the car above it) out over a wider area of the tread, lessening the amount of grip per square inch of tire-tread surface on slippery surfaces (more so than on dry ones, where the rubber grips more), although the type of rubber/silicone tread compound used can help minimize this. That's why the best winter tires are often relatively tall and narrow.....and why RWD ultra-wide tire cars ike the Dodge Viper and Corvette can be virtually useless in the winter.

One more thing to take into account with low-profile tires is that, all else equal, you will have less impact-protection for both the tire and the wheel if you hit a sharp bump or pothole. Tire shops do an amazing amount of buisness each year replacing wheels and low-profile tires from rough-road damage.

Chocolate

I would highly recommend anyone interested in this topic to read these two articles:

http://grassrootsmotorsports.com/articles/speed-holes/

http://www.caranddriver.com/features...d-tires-tested

Interestingly there was no measureable difference in dB between 15" and 18". The VW Golf measured 70dB for most of the readings at 70mph. I have a professional dB meter and my ES measures between a low of 61.6 and mid 60s without nearby traffic, depending on the road.

Chocolate

Good info

I was only wondering whether the extra width of 225 would outweigh the slight extra amount of sidewall, since 215/55/17 already has a lot of tire flex. Noise isn't a concern, only ride. Any thoughts?

mmarshall

Thanks. I posted that for a reason. A lot of people today simply judge tires/wheels by their looks and/or how much they fill up the wheel-wells. Huge wheels and wide/thin rubber-band tires today are considered "cool" , but many potential buyers don't really know (or don't stop and think about) what they are actually getting.

Aron9000

I'm running 18" wheels on my SC and I'm fine with the ride. But then again all the roads in my area are EXCELLENT. I wouldn't be running this type of wheel/tire package if I lived up north where the roads are crap from all the freeze/thaw cycles.

spwolf

it will certainly ride a bit better, compared to same tire with less sidewall.

So make sure you select softer tire, not hard one... that will also influence it. If you select fatter tire but also harder one, then you are back to square 1, or worse.

mmarshall

Yes, I agree. The smoother the roads, the less objectionable the ride-quality is with low-profile tires and large wheels. The best examples, of course, are probably the speed-unlimited sections of the German Autobahn. They have to keep that road mirror-smooth simply by necessity (just like on a race track)....the slightest bump or tire disturbance at those speeds could easily lead to loss of control.

On the combination of frost-damaged roads and low-profile tires, though, there's potentially more to worry about than just a noisy/unpleasant ride. Because of the thinness of the sidewalls, a tire/wheel impact with a sharp bump or pothole-rim could lead to tire failure or a cracked alloy wheel.